1215720001 has 4 divisors (see below), whose sum is σ = 1241586432. Its totient is φ = 1189853572.

The previous prime is 1215719977. The next prime is 1215720013. The reversal of 1215720001 is 1000275121.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 1215720001 - 2⁵ = 1215719969 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1215720041) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 12933145 + ... + 12933238.

It is an arithmetic number, because the mean of its divisors is an integer number (310396608).

Almost surely, 2^1215720001 is an apocalyptic number.

It is an amenable number.

1215720001 is a deficient number, since it is larger than the sum of its proper divisors (25866431).

1215720001 is an equidigital number, since it uses as much as digits as its factorization.

1215720001 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 25866430.

The product of its (nonzero) digits is 140, while the sum is 19.

The square root of 1215720001 is about 34867.1765561825. The cubic root of 1215720001 is about 1067.2787288805.

Adding to 1215720001 its reverse (1000275121), we get a palindrome (2215995122).

The spelling of 1215720001 in words is "one billion, two hundred fifteen million, seven hundred twenty thousand, one".